Signaling system and apparatus therefor



April 16, .1940.

P. P. HORNI SIGNALING SYSTEM AND APPARATUS THEREFOR Filed April 2'7,` 1958 FIG. l'

INVENTOR. PAU L P. HORN! Patented Apr. V16, 1940 UNITED srA-TE s oFFicl-z siGNA-LING SYSTEM -ANnArrARA'rUs 'murieron Paul P. Horni, Newark, N.A J. Application April 27, 1938,. Serial No.` 204,527-

3 Claims.V

Thisinventiongrelates:toelectric signaling and is particularly adapted.` for use; in: conjunction with nre-alarms, and isv a continuation in partof co-pendingY applications for.. Electric signalingl 5. system; Ser.'` No; 85,312r,;and;for Electric signaling apparatus, Ser. No. 85,311.

In re alarm signaling,l wherein the transmitters areof the noir-interfering succession type,

it is Well known that if in the event thegcoiliof one; of the. noninterfering magnets; were to'A become.

open, the non-interfering qualities ofthe trans,-

mitters Werelost.v .'It-:istherefore an object of this invention to provideaafsignaling transmitter:

such that in :the 'event L one aof ,the non-'interfer-v 15 ence. coils thereinshould become open; theftrans.-

mitter. .would i still` retain its non-interfering.

qualities.

It is furtherv an object of thisv inventionto pro-f vide a. signaling:v arrangement sozthat i a` Aplurality mayfbe- .utilizedso thatzthe signaling 4system wlill b materially improvedvinzits. operative. effective,-l

ness.

A further'objectistoprovide positive operation ofl signal transmitting .mechanisms .and-g prevent.

the failure thereof: due .-to.: an open coil .in the noninterference. magnett by providing ani auxiliary5 electrical path to complete the circuit.

A further object of the invention is the proviaroundthe coil so, .that a. plurality` ofthese comr binations may bev`v included ina.. series circuitso that the opening of any coil or coils, will not disrupt electrical continuity ofthe series circuit.

serially connected signal transmittersv having magnets for non-interferenceand other purposes and to provide these magnets with continuously effective current 'oy-pass so thatl opening the t winding of any-magnet' will'causethe current4 to be diverted through its associated by-pass and avoid disruption of electrical continuity'in the signaling system.

'45 Other and further objects, and advantagesiof' of: the signaling transmitters referred. to herein.V

sion of a coil. and analternate. current path..

Affurther,objectfof"the'invention is to provide a signaling System comprising a plurality of Fig. 2 is a'differentconditionof. the manually operated switch s-howntin-Fig. 1. 4

. E'igs. 3 and 4 are diagrammatic'representation of current pathsfin the; signaltransmitting unit when the circuit is. closedthroughthedoor shunt 6; switching device.' l

. Fig. 5 is amodification of the shunts. This invention) relates; not onlytothey normallyv closed metallic. loop circuit: but also provides ad' vantages for Ause' in conjunction withr signaling 10..,

circuits.v providing ang-round return-or .auxiliary (signalingconductor.`

The diagrammatic'representation-shownin l, has a suitable direct current energy-source;

hereshown.`- as va battery U33, connectedacross 155; f l

the IinesLI-LZ, with aregister I l connected yin one sideof the line. .Two filters, such as-icon densers, are shown connected across the line to a common terminal H10, which termina1 is ycon- Y nected to a conductor having kimpressed thereon 20V` a multiplicityof suitablealternatingv currents o f diierent andgdisi'finctA frequencies, froma.multi frequency alternatingy current energy unit m5,; the other side of said-alternating current;l unit.r being` suitably connected* to. selective band passfilters H16, l'iand H38, and correspondingimani-` festationldevices; |06,.I01 and IIJB` respectively, a filter-and manifestation device being. supplied 'for cachoty saidf frequencies, and-responsive there-to.- Theother sides ofthe riilter manifestar,l tion means. areV connected totacommon return or. linel L3.

In Fig. 2 the switch is shown `in af position to l meet emergency'` signaling requirements, whenY one side-ofthenline, as LI, becomesabnormally 35 open.` Battery |03, is connected serially between vthe lines yL3 and L2 to supply energy for directg currentoperation. A low passflter |04, is-inserted in the line to permit passage therethrough of direct current, and to prohibitpassage of4 49 alternating current and a consequential detri-v mental shunting' ofthe alternating current cen-A trai oiiice apparatus.. j Thefelectrical current path may be best `traced* by, referring toV the drawing in Figs- 3' and 4, 4.15? which represent-similar electrical parts andcon nections` in a transmitter as contemplated by this invention, when the box shunt 95,y is openand4 the, docrshunt. is closed. In each of the views, lines,Y

LI, L2 and L3, are disposed so as tobe used in 5 0: .y

reference to similar'line connections in Fig. 1, with the central oiiice equipment.

In the Apatent to F. W. C ole, #1,058,728, and'; manyother patents, the-art shows it isfoldtd establish a -telegraphic communication .from one; 5.5.-;

side of the metallic loop or line, and a ground, as an emergency circuit in case of a malcondition of the regular line. Once the emergency circuit is established the transmitter mechanism again proceeds to seize the line in an attempt to reach the central station. Further it is Well known in the art and further disclosed in the copending application Ser. No. 85,311, that a pair of movable contacts are periodically opened and closed in response to the indentations of vthe station identifying code wheel. In Figs. 3 and 4 these movable contacts are referred to as contact sets 62 and 62'.

In regard to the establishing of the emergency circuit the prior art discloses as in the Cole patent mentioned above, and also in the co-pending application Ser. No. 85,311, that it is well known to those skilled in the art khow a circuit is established between the signal transmitter and the auxiliary conductor or ground, the exact mechanism therefore, being immaterial to the present application.'k Suice it to say that when the auxiliary circuit is completed, the member 84 engages the contact 85 which is merely symbolical of means for closing a circuit.`

A direct current circuit path, `Fig. 4, may be traced over'line LI, from negative battery |03, Fig. l, contact set 62, coil 98 and its shunt 90, to a terminal |4| through coil 93 and its shunt 99', contact set 62', line L2, register |0I, (Fig. l), back to positive battery. When the code wheel actuates the contact sets 62-62, the direct current will be interrupted to transmit the station identifying code #number corresponding to the teeth on the code wheel, and actuate register l In Fig. l3 since the impedance of the magnets 98-98 may be such as to be prohibitive to the passage of alternating current, substantially none of the alternating current passes through thel magnets, but does pass almost entirely through the magnet shunts. Switch 95 being closed, one frequency selected from a plurality of frequencies, by the selective band pass lter |33, passes from one side of the central oflice alternating current source, over lines L|--L2, through contact sets 62-62, resistors or shunts 99--99, unite atr terminalv |4`|, passes through 96 and filter |33, over L3,`1"llter |06, actuating relay '|06', back to the other side of the alternating current energy source. It will thus be seen that each impulse of' the v'code wheel circuit controlling contacts also controls an alternating current, to create a coded signal on the register |24, the initial impulsing current frequency of which is common to alltransmitters in the particular loop circuit and may be utilized by any successful transmitter.

A high pass lter |34 is connected across each boX shunt switch to provide alternating current circuit continuity to any Waiting box, during operation of any successful transmitter to transmit an instantaneous signal. In Fig. ll-,when the box is actuated, an instantaneous uncoded signal is received at headquarters, before the conventional coded signal, regardless of whether or not the signaling loop is busy. Each transmitter has a selective iilter |35, and an independent manifestation device and corresponding selective filter,

two sets of which are shown in Fig. 1, as |0'|-|0'|k and |08-|08 respectively, and an independent alternating current of a distinctive frequency for each of said selective iilter sets, originatingv in |05. Therefore, in Fig. 3 a current path may be traced from the alternating current energy source,

over L|-L2, to the signaling loop andtrans mitters, to switch 91, selective filter |35, L3, back to the alternating current energy source.

An abnormal open circuit in the loop would cause the transmitter movement, as heretofore set forth, to actuate switch 84, Fig. 4, and close a circuit between said switch and a contact Assume the abnormal open circuit occurred in the L| side of the line. The switch |09 would then be changed automatically,s or by a headquarters attendant, to the position shown in Fig. 2, whereby a direct current circuit path may be traced from positive battery, through register |0I, line L2, contact set 62', magnet and shunt 98-99"respectively, terminal IM, contact 85', switch 04, low pass lter |36 which is prohibitive to passage of alternating current but passes direct current over L3, back to negative battery. A low pass filter |04, is also shown in L3 in the lcentral oice apparatus, to prevent passage of to effect actuation of register=|2. The instan-v taneous uncodedsignal `would be received normally as heretofore described.

By providing non-inductive shunting members foreach magnet, theeiective inductance of each parallel combination is substantially eliminated. Thus, if several transmitters areactuated at substantiallythe sameinstant,v the contacts of the.' successful transmitter must make andbreak current in a circuit in which the magnets of all the waiting transmitters are serially connected. This added induction, in the signaling pathtends to hasten the deterioration of the signaling contacts, since the energy stored in all magnets must bedissipated in the'form of an arc occurring at each separation of the vcooperating signaling contacts. The ShuntngmemberS, as herein disclosed, provide suitable and convenient means for absorbing this energy of self-inductance and thus increase'v contact life.

At each closure of the signaling contacts, the

battery voltage is opposed by a counter electromotive force of self-inductance and the currentl gradually rises to-a finalvaluaio Which vis equal-` where e is the voltage of thebattery'" and ris the total" resistance of the," circuitfThe" current,`

at lany instant may be expressed: A

y feto- -ff'fa where e represents the base of natural logarithms, t represents the elapsed time from the instant of closure ofthe'contacts, r represents the total re.

sistancein the circuit-limiting 'thenal current value i0, and L represents the total effective linductance in the circuit.

From, this ratio will be seen since the time required for the current to attain only one-half of its iinal'value equation, theimportance of the 'of the lfinalof the circuit in henrys and 1' isthetctal resistance in ohms which limits` the flow ofl current rafter the steady state hasbeen reached;

In the construction ofall transmitters of the positive non-interfering type, a denite time in terval elapses between the instant of closure ofr the signaling contacts and the instantlthat the mechanical support is withdrawn fromthe noninterference armature.' This action takes place as the contacts are closed bythe sloping edge of each tooth on the code wheel. No suchtime interval is included or required when the contacts open since the overlapping action ofthe mechanism insures mechanical support'for the armature prior to the opening of the contacts. p

Thus, it will be seen that any successful transmitter must not only make and break, the current owing through all magnets inv the circuit, but it must also includea period of overlap so that the current will attain a suicient value to vretain the non-interference armature in itsportative position before mechanical support is withdrawn. If mechanical support would be withdrawn before sufticient electrical support is substituted therefore, the non-interference armature 'will dro'p back to its unattracted position andthe transmitter will forfeit its control of the circuit. Thus, if several transmitters are actuated simultaneously, or substantially so, eachupon actuation introducing itsA non-interference mag-1 nets serially into the circuit, a' condition may occur whereby no signal will be received from some of them. Upon actuation each transmitter includes its magnets in the series circuit connecting the several transmitters, thus increasing both the inductance and the resistance for the entire circuit. The introduction of the resistance reduces the final value` of current, i0 which will flow upon reaching the steady state. If the ratio,

transmitter in its portative position until after removal of mechanical support from said. armature and its lapse into the unattracted position. Another of the transmitters, attempting to seize the line and transmit its signal, will in turn be similarly unsuccessful if its period of overlapping action vis no longer than that of the first transmitter. Thus all of a group of transmitters will be unable to transmit their signals because of the excessive inductance in the circuit. It is probable, that after a considerable delay, during which certain transmitters will complete their cycle of operation and will have come to rest, shunting out their magnets, one or more of the group may succeed in transmitting their signals, but several signals will have been unnecessarily lost.

The provision of shunting members as described greatly reduces the effectiveness of the self-inductance of the magnets by permitting current to iiow through the shunting members substantially instantaneously. Thus the presence of a plurality of non-interference magnets in the series circuit, introduced either by faulty contact at the movement shunts or by actuation of the respective transmitters, will exert no harmful decurrent.

These non-inductive shunting members-have extremely high'voltages of selfinduction accom-/ panying vrapid changes in current.

' Figs. 3 and 4 show schematically a single transe' mitter connected in the loop circuit thatA is; be'` tween terminals Ll and L2. However it is Well known that several boxesmay be, and usually are, connected serially in the loop circuit. Whilev the drawingdoes not show specifically more than yone box inthe loop circuit, it is to be understood that this is done simply for the purposezof presenting a concise and clear explanation. of the"v operation of thepresentr invention, and it iste be understoodthat several boxes'are serially connected in either or both sides of lines Ll and L2. While the drawing showsthat the non-interi ference magnets each have a shunt which is made of carbon and therefore non-inductive, it is neverthelessftruethat under certain'conditionsl the shunt for *the individual 'magnets'may be a coil, therefore, it is set forth herein, that vthe f of performing yits desired objective. 1

y The transmitter disclosedherein is shownv co'nnected to a circuit having'anauxiliary return' path, yet it is to be understood that this` invention may be employed Withoutthe functions of the emergency switching means, for use on a system not provided with an auxiliary circuit return path, such as a ground.

gree of retarding action uponthe flow of vsignaling l as: p

When signaling on a system equippedl for'- transmission overa metallic loop only, in the event of both coils of the non-interfering magnetshaving an open circuitl in theirrespective windings, the signal would be sent, but the noninterfering succession feature would vbe suspended. vSince the protective shunts are permanently connected across the coils, the necessity of providing mechanical motions and switching vention.`v f

If desired, many of the advantages `of the invention may be realized without providing special y shuntmembers as described above. Referring to Fig. 5, coils 98 and 98 are connected -in multiple eachserving as a shunt for the other. Utilizing this arrangement, substantially one-halfv` the signaling current will flow through each winding. If either winding becomes open, circuit continuity will be maintained throu-gh the other, and in addition, the operative magnet` will serve to performfthe non-interference and` succession functions. Furthermore, advantagesof non-in `ductive shunts are approximated, since the inductive components of the magnet impedances are eiTective in the circuit as aparallel combination instead of the customary series combination` heretofore employed. Thus, if magnets of the4 same inductance were used. in either case, the' total inductance of the parallel combination would be about one quarter of -the inductance of the series combination. y f f For all practical purposes, however, the above described condition in which both non-intere.

:sol ymeans is entirely eliminated by this novel inpossibility of a single magnet being in inoperative condition. y

If the transmitter is arranged, as contemplated above, so that effective non-interfering and succession functions may be performed under conditions of normal line current by either one of a pair of magnets, then the provision of the shunts will assure a novel and desirable feature, namely, the transmission of signals with complete non-interfering and succession operation,

` even though one of the magnets may be disabled.

In the present invention, voice currents and currents of like character will pass more freely through the shunting members, if of non-inductive design, thereby avoiding the necessity for providing additional apparatus for this purpose.

Certain specific detailed features and advantages of the invention have been herein set forth, but the invention is not limited thereto, as changes and alterations may be and may become apparent to those skilled in the art Without departing from the spirit thereof as defined by the appended claims.

What I claim as new and desire to secure by u Letters Patent of the United States is 1. In signaling apparatus of the class described having a current path, a non-interference electromagnet connected therein, said electromagnet comprising a multiplicity of serially connected coils, and a-n individual permanent by-pass for each of said coils each having characteristics a1` lowing effective energization of its coil so that in the event one of said coils should become ineffective the non-interference properties of said electro-magnet will be retained.

2. In a signaling system comprising an energy source connected to a normally closed current path having a manifestation device therein, a multiplicity of non-interfering signal initiating stations serially connected in said path, a plurality of non-interference electro-magnets in each of said stations having a permanently connected shunt for each electromagnet each having characteristics allowing effective energization of its coil, so that in the event of an open circuit in one of said electromagnets, the non-interference signal operation of said initiating station will be maintained.

3. In a signaling system comprising an energy source connected to a normally closed current path having a manifestation device therein and a multiplicity of non-interfering signal initiating stations connected in said path; a plurality of non-interference electromagnets in each of said stations, a permanently connected shunt for each of the electromagnets, the resistance of the per-k manently connected shunt in each station across each electromagnet being such that the shunt will permit sufcient current to flow through the effective electromagnet windings to accomplish its non-interference functions.

PAUL P. HORNI. 

